Differential Growth Responses of Wheat Seedlings to Elevated CO2

Hamid Reza Eshghizadeh,Morteza Zahedi,Samaneh Mohammadi

doi:10.15835/nsb10310286

Hamid Reza Eshghizadeh, Morteza Zahedi + Show 1 more

Open Access

https://doi.org/10.15835/nsb10310286

Copy DOI

Abstract

Intraspecific variations in wheat growth responses to elevated CO2 was evaluated using 20 Iranian bread wheat (Triticum aestivum L.) cultivars. The plants were grown in the modified Hoagland nutrient solution at a greenhouse until 35 days of age using two levels of CO2 (~380 and 700 µmol mol–1). The shoot and root dry weights of the wheat cultivars exhibited average enhancements of 17% and 36%, respectively, under elevated CO2. This increase was associated with higher levels of chlorophyll a (25%), chlorophyll b (21%), carotenoid (30%), leaf area (54%) and plant height (49.9%). The leaf area (r = 0.69**), shoot N content (r = 0.62**), plant height (r = 0.60**) and root volume (r = 0.53*) were found to have important roles in dry matter accumulation of tested wheat cultivars under elevated CO2 concentration. However, responses to elevated CO2 were considerably cultivar-dependent. Based on the stress susceptibility index (SSI) and stress tolerance index (STI), the wheat cultivars exhibiting the best response to elevated CO2 content were ‘Sistan’, ‘Navid’, ‘Shiraz’, ‘Sepahan’ and ‘Bahar’, while the ones with poor responses were ‘Omid’, ‘Marun’, ‘Sorkhtokhm’ and ‘Tajan’. The findings from the present experiment showed significant variation among the Iranian wheat cultivars in terms of their responses to elevated air CO2, providing the opportunity to select the most efficient ones for breeding purposes.

Highlights

Wheat is one of the most important crops as it provides approximately 20% of the energy and 25% of the protein requirements of the world’s population of 6.6 billion (Pocketbook, 2015; Reddy and Hodges, 2000)
Bourgault et al (2013) found that average leaf area of wheat plants was increased by 30% under elevated CO2 concentration of 700 μmol mol-1 compared with its normal ambient level (400 μmol mol-1)
The current atmospheric carbon dioxide concentration of 400 μmol mol–1 is considered as a limiting factor to photosynthesis rate in C3 plants

Summary

Introduction

Wheat is one of the most important crops as it provides approximately 20% of the energy and 25% of the protein requirements of the world’s population of 6.6 billion (Pocketbook, 2015; Reddy and Hodges, 2000). It ranks first among cultivated field crops in Iran with an average per capita consumption of about 220 kg, consumed both directly and indirectly (Khajehpour, 2013). Increasing carbon dioxide concentration improves photosynthesis in C3 plants such as wheat via prevention of photorespiration; wheat yield is expected to increase under elevated CO2 assuming that other growth factors remain within optimal limits (Amthor, 1997). Bourgault et al (2013) found that average leaf area of wheat plants was increased by 30% under elevated CO2 concentration of 700 μmol mol-1 compared with its normal ambient level (400 μmol mol-1). Pal et al (2005) reported that wheat plants recorded a greater photosynthetic rate, plant height, leaf surface area and plant dry mass at all growth stages (40, 60, and 90 d after sowing) under an elevated CO2 of 600 ± 50 μmol mol-1 than those grown under the ambient CO2 of 350 ± 50 μmol mol-1

Results

Discussion

Conclusion